Samuel de Carvalho Dumith

Physical activity change during adolescence: a systematic review and a pooled analysis

BACKGROUND It is presumed that physical activity (PA) level declines during the lifespan, particularly in adolescence. However, currently, there is no study that quantifies these changes and pools results for a common interpretation. Therefore, the purpose was to systematically review the international literature regarding PA change during adolescence, and to quantify that change according to a series of study variables, exploring gender-and-age differences. METHODS An electronic search was conducted in the Medline/PubMed and Web of Science databases. Longitudinal studies with, at least, two PA measures throughout adolescence (10-19 years old) or the first PA measure during childhood and the second one during adolescence were selected. From each article, study project name, country, year of the first data collection, sample size, baseline age, follow-up duration, characteristics of the instrument (type, recall time, PA intensity and PA domain), unit of PA measure and report of statistical significance were collected. RESULTS Overall, 26 studies matched the inclusion criteria. Most were carried out in the USA, assessed PA by questionnaire, and found a decline in PA levels during the adolescence. On average, the mean percentage PA change per year, across all studies, was -7.0 (95% confidence interval: -8.8 to -5.2), ranging from -18.8 to 7.8. The decline was significant according to most sub-groups of variables analysed. Although earlier studies revealed a higher PA decline in boys, the decline has been greater in girls in more recent studies (commenced after 1997). Moreover, although the decline among girls was higher in younger ages at baseline (9-12 years), it was higher in older ages (13-16 years) among boys. CONCLUSIONS The decline of PA during adolescence is a consistent finding in the literature. Differences between boys and girls were observed and should be explored in future studies. Interventions that attempt to attenuate the PA decline, even without an increase in PA levels, could be considered as effective.

Worldwide prevalence of physical inactivity and its association with human development index in 76 countries

OBJECTIVE To describe the worldwide prevalence of physical inactivity and to analyze its association with development level of each country. METHODS Pooled analysis of three multicenter studies, conducted between 2002 and 2004, which investigated the prevalence of physical inactivity in 76 countries, and comprised almost 300,000 individuals aged 15 years or older. Each study used the International Physical Activity Questionnaire to assess physical inactivity. The level of development of each country was analyzed by the Human Development Index (HDI). RESULTS The crude worldwide prevalence of physical inactivity was 21.4% (95%CI 18.4-24.3), being higher among women (mean=23.7%, 95%CI 20.4-27.1) than men (mean=18.9%, 95%CI 16.2-21.7). It ranged from 2.6% (in Comoros) to 62.3% (in Mauritania), with a median equal to 18%. After weighting for the total population of each country, the worldwide prevalence of physical inactivity was 17.4% (95%CI 15.1-19.7). There was a positive association between HDI and prevalence of physical inactivity (rho=0.27). Less developed countries showed the lowest prevalence of physical inactivity (18.7%), while physical inactivity was more prevalent among the most developed countries (27.8%). CONCLUSIONS One out of five adults around the world is physically inactive. Physical inactivity was more prevalent among wealthier and urban countries, and among women and elderly individuals.

Evolução da pesquisa epidemiológica em atividade física no Brasil: revisão sistemática

OBJECTIVE To describe the evolution of the epidemiological research on physical activity in Brazil. METHODS A systematic review of the literature was carried out in electronic databases (Medline/PubMed, Lilacs, Ovid, Science Direct, BioMed Central and High Wire), non-indexed Brazilian journals, query by specific authors, and contact with other researchers. The inclusion criteria were: the sample should be representative of a defined population; sample size equal to or greater than 500 individuals; data collection in Brazil; measurement of physical activity; and report of data on this variable. RESULTS A total of 42 studies were reviewed. The first study was published in 1990, and there has been a clear growth in the number of publications since 2000. Great regional disparities were seen and most studies were carried out in the Southeast and South regions. Almost all studies (93%) used questionnaires but operational definitions of sedentary lifestyle and questionnaires used varied markedly across studies preventing result comparisons. CONCLUSIONS Although the literature on physical activity in Brazil has quantitatively increased, methodological limitations make it difficult to compare study results. Therefore, standardization of instruments and definitions is essential for the improvement of scientific knowledge in the area.

Physical activity as a predictor of adolescent body fatness: a systematic review

Adolescent obesity has increased dramatically in several countries in recent decades; however, the contribution of physical activity level to adolescent adiposity requires clarification. This article investigates the effect of physical activity on subsequent levels of adiposity in adolescence. The methodological aspects of the studies included in this article, particularly in terms of measurement accuracy for both exposure (physical activity) and outcome (adiposity) variables, are also evaluated. Systematic searches of the literature were undertaken using online databases, including PubMed/MEDLINE, examination of citations and contacting of authors. The online databases were searched from their earliest records until 2007. Only longitudinal studies with 50 or more adolescents were included. Two independent reviewers assessed the quality of the studies using the Downs and Black checklist. Thirteen observational, five experimental and six quasi-experimental studies (without a control group) were identified. Almost all studies were carried out in high-income settings and showed protective effects of physical activity for both prevention and treatment of adolescent obesity. However, experimental studies undertaken with obese adolescents at baseline usually combined physical activity with dietary changes, making it difficult to assess the effect of physical activity itself on the treatment of obesity. Physical activity estimated from questionnaires and body mass index (BMI) were the most frequently used measures. Despite the feasibility of using these approaches in epidemiological studies, significant limitations are evident. Questionnaires are subjective and adolescents may not report physical activity level accurately. Furthermore, BMI is not an accurate measure of fatness for adolescents, as it is also associated with lean mass, hence bias may arise from its longitudinal association with physical activity level. Despite the majority of studies reviewed showing protective effects of physical activity on adiposity, particularly in individuals who are obese at baseline, the current literature on this issue is sparse and several methodological drawbacks are evident. The main limitations relate to a lack of validity in the measurements of both physical activity and body composition. Further studies are needed in order to generate evidence-based recommendations for the quantity and quality of adolescent physical activity required to prevent or treat adolescent obesity.

Uso regular de serviços odontológicos entre adultos: padrões de utilização e tipos de serviços

The aim of this study was to estimate the prevalence of regular use of dental services by adults and identify groups where this behavior is more frequent. A cross-sectional population-based study was carried out in Pelotas, southern Brazil, including 2,961 individuals who answered a standardized questionnaire. Overall prevalence of regular use of dental services was 32.8%. The following variables were positively associated with regular use: female gender, age >or= 60 years, no partner, high educational level, high economic status, private service user, good/excellent self-rated oral health, and no perceived need for dental treatment. Those who had received orientation on prevention and expressed a favorable view towards the dentist had higher odds of being regular users. Especially among lower-income individuals, regular use was infrequent (15%). When restricting the analysis to users of public dental services, schooling was still positively associated with the outcome. Dental services, especially in the public sector, should develop strategies to increase regular and preventive use.O objetivo deste estudo foi avaliar o uso regular de servicos odontologicos entre adultos, identificando grupos nos quais esse comportamento e mais frequente. O estudo foi realizado em Pelotas, Rio Grande do Sul, Brasil, com desenho transversal de base populacional, envolvendo 2.961 individuos, que responderam um questionario estruturado. A prevalencia de uso regular encontrada foi de 32,8%. Estiveram positivamente associadas ao uso de forma regular as seguintes caracteristicas: ser do sexo feminino, ter idade < 60 anos, nao ter companheiro, ter alta escolaridade, ter maior nivel economico, usar servicos privados, ter autopercepcao de saude bucal boa/otima, nao ter autopercepcao de necessidade de tratamento, ter recebido orientacao sobre prevencao e ter manifestado opiniao favoravel ao profissional. O uso regular foi pouco frequente, especialmente entre os menos favorecidos (15%). Restringindo a analise apenas para usuarios do servico publico, observou-se maior utilizacao regular entre os mais escolarizados. Os servicos de saude, em especial o publico, devem trabalhar a fim de incrementar o uso regular e preventivo.O objetivo deste estudo foi avaliar o uso regular de servicos odontologicos entre adultos, identificando grupos nos quais esse comportamento e mais frequente. O estudo foi realizado em Pelotas, Rio Grande do Sul, Brasil, com desenho transversal de base populacional, envolvendo 2.961 individuos, que responderam um questionario estruturado. A prevalencia de uso regular encontrada foi de 32,8%. Estiveram positivamente associadas ao uso de forma regular as seguintes caracteristicas: ser do sexo feminino, ter idade < 60 anos, nao ter companheiro, ter alta escolaridade, ter maior nivel economico, usar servicos privados, ter autopercepcao de saude bucal boa/otima, nao ter autopercepcao de necessidade de tratamento, ter recebido orientacao sobre prevencao e ter manifestado opiniao favoravel ao profissional. O uso regular foi pouco frequente, especialmente entre os menos favorecidos (15%). Restringindo a analise apenas para usuarios do servico publico, observou-se maior utilizacao regular entre os mais escolarizados. Os servicos de saude, em especial o publico, devem trabalhar a fim de incrementar o uso regular e preventivo.

Prática de atividade física e sedentarismo em brasileiros: resultados da Pesquisa Nacional por Amostra de Domicílios (PNAD) 2008

Population surveys are a key component of the relevant activities for public health. There is growing interest in identifying behavioral aspects which influence individual and collective health, such as physical activity (PA). The aim of this study is to present PA data from the 2008 Brazilian National Household Survey (PNAD) according to regional distribution and the socio-demographic characteristics. A partnership between the Brazilian Institute of Geography and Statistics and the Ministry of Health was responsible for preparing the health supplement of the questionnaire. The sample size was 292,553 individuals. The proportion of subjects practicing PA at the recommended levels in leisure time was 10.5%, exactly the same proportion of subjects reporting active transportation to and from work. Males and younger adults were more active; schooling was directly related to leisure-time PA and inversely associated with transport-related physical activity. One fifth of the Brazilians did not report any physical activity at all and 35.7% watch TV for 3 hours or more, on average, per day. These data may help design public policies aimed at promoting health, in particular through PA, which may positively influence on the quality of life of the Brazilian population.

Diferenças socioeconômicas entre autoclassificação e heteroclassificação de cor/raça

OBJETIVO: Avaliar (1) a consistencia entre cor/raca autoclassificada e determinada por entrevistador segundo variaveis socioeconomicas e demograficas e (2) a magnitude das desigualdades etnico-raciais de renda e condicao socioeconomica utilizando cor/raca autoclassificada e heteroclassificada. METODOS: Estudo transversal de base populacional com individuos >20 anos (N=3.353), de ambos os sexos, conduzido na zona urbana de Pelotas, Rio Grande do Sul, em 2005. O processo de amostragem ocorreu em dois estagios e a coleta de dados foi domiciliar. Foram utilizados questionarios padronizados e pre-codificados, aplicados sob a forma de entrevistas face-a-face. A consistencia entre cor/raca autoclassificada e determinada pelo entrevistador foi verificada por meio da proporcao de concordância e estatistica kappa. Desigualdades etnico-raciais de renda e condicao socioeconomica foram estimadas com os modelos de regressao linear e logistica ordinal, ajustando-se para sexo, idade e escolaridade. RESULTADOS: A taxa de resposta foi de 93,5%. Apesar da alta reprodutibilidade observada para cor/raca, verificou-se tendencia de branqueamento dos entrevistados. Autoclassificados pardos e pretos tiveram 1,4 e 1,5 vezes mais chance de serem classificados como brancos do que como pretos e pardos, respectivamente. Os valores de kappa foram mais altos nos grupos socialmente desfavorecidos. Evidenciaram-se desigualdades etnico-raciais de renda e condicao socioeconomica, as quais foram ligeiramente maiores com cor/raca determinada por entrevistador. CONCLUSOES: A classificacao racial apresenta tendencia ao branqueamento dos participantes por parte do entrevistador. Pardos e pretos encontraram-se em desvantagem socioeconomica quando comparados aos brancos.

Risk factors for suspected developmental delay at age 2 years in a Brazilian birth cohort

de Moura DR, Costa JC, Santos IS, Barros AJD, Matijasevich A, Halpern R, Dumith S, Karam S, Barros FC. Risk factors for suspected developmental delay at age 2 years in a Brazilian birth cohort. Paediatric and Perinatal Epidemiology 2010; 24: 211–221. Many children are at risk of not achieving their full potential for development. Epidemiological studies have the advantage of being able to identify a number of associated factors potentially amenable to intervention. Our purpose was to identify risk factors for suspected developmental delay (SDD) at age 2 years among all children born in the city of Pelotas, Brazil, in 2004. This study was part of the 2004 Pelotas Birth Cohort. The Battelle Screening Developmental Inventory (BSDI) was administered to cohort children at age 2 years. A hierarchical model of determination for SDD with confounder adjustment was built including maternal sociodemographic, reproductive and gestational characteristics, as well as child and environmental characteristics. Multivariable analysis was carried out using Poisson regression. Prevalence ratios (PR) and 95% confidence intervals [95% CI] were calculated. In the results, 3.3% of the 3869 children studied screened positive for SDD. After confounder control, children more likely to show SDD were: those with positive BSDI at age 12 months (PR = 5.51 [3.59, 8.47]); with 5-min Apgar <7 (PR = 3.52 [1.70, 7.27]); with mothers who had <4 years of schooling (PR = 3.35 [1.98, 5.66]); from social classes D and E (PR = 3.00 [1.45, 6.19]); with a history of gestational diabetes (PR = 2.77 [1.34, 5.75]); born <24 months after the last sibling (PR = 2.46 [1.42, 4.27]); were not told child stories in the preceding week (PR 2.28 [1.43, 3.63]); did not have childrens literature at home (PR = 2.08 [1.27, 3.39]); with low birthweight (PR = 1.75 [1.00, 3.07]); were born preterm (PR = 1.74 [1.07, 2.81]); with <6 antenatal care appointments (PR = 1.70 [1.07, 2.68]); with history of hospitalisation (PR = 1.65 [1.09, 2.50]); and of male sex (PR = 1.43 [1.00, 2.04]). These risk factors may constitute potential targets for intervention by public policies and may provide help to paediatricians in preventing developmental delay.

Associations of Birth Order With Early Growth and Adolescent Height, Body Composition, and Blood Pressure: Prospective Birth Cohort From Brazil

Birth weight has been inversely associated with later blood pressure. Firstborns tend to have lower birth weight than their later-born peers, but the long-term consequences remain unclear. The study objective was to investigate differences between firstborn and later-born individuals in early growth patterns, body composition, and blood pressure in Brazilian adolescents. The authors studied 453 adolescents aged 13.3 years from the prospective 1993 Pelotas Birth Cohort. Anthropometry, blood pressure, physical activity by accelerometry, and body composition by deuterium were measured. Firstborns (n = 143) had significantly lower birth weight than later borns (n = 310). At 4 years, firstborns had significantly greater weight and height, indicating a substantial overshoot in catch-up growth. In adolescence, firstborns had significantly greater height and blood pressure and a lower activity level. The difference in systolic blood pressure could be attributed to variability in early growth and that in diastolic blood pressure to reduced physical activity. The magnitude of increased blood pressure is clinically significant; hence, birth order is an important developmental predictor of cardiovascular risk in this population. Firstborns may be more sensitive to environmental factors that promote catch-up growth, and this information could potentially be used in nutritional management to prevent catch-up “overshoot.”

Prevalence and correlates of physical activity among adolescents from Southern Brazil.

OBJECTIVE To estimate the prevalence and identify correlates of physical activity among adolescents. METHODS Cross-sectional study nested within a cohort of 4,325 subjects from the city of Pelotas, Southern Brazil, aged 14-15 years in 2008. Physical activity was analyzed using three different approaches: (1) prevalence of any leisure-time physical activity; (2) prevalence of any active commuting to school; and (3) prevalence of engaging in at least 300 minutes per week of both (1) and (2) combined. Independent variables included sociodemographic, behavioral, social, and biological characteristics, and number of different leisure-time physical activities practiced. Statistical analyses were carried out using Poisson regression. RESULTS The proportion of adolescents involved in any type of leisure-time physical activity was 75.6%, while 73.4% displayed some form of active commuting to school. Prevalence of total physical activity score (>300 min/week) was 48.2%, being greater among boys (62.6%) than among girls (34.5%). Furthermore, prevalence increased along with the number of physical activity modalities practiced (p<0.001). Factors associated with greater physical activity (leisure+commuting) at the recommended levels were: nonwhite skin color, having failed at school, and playing videogames. Lower socioeconomic status, more time spent on the computer, and parental physical activity were associated with the outcome only among girls. CONCLUSIONS Less than half the adolescents reached recommended levels of physical activity, and this proportion tended to decrease among subjects with higher socioeconomic level. Associated factors were different for leisure-time and commuting. Engaging in a wide variety of physical activities should be encouraged already during childhood.